During the fabrication of wire bonds, copper wire, as well as its plated varieties, must be worked in the presence of forming gas or a similar anoxic gas in order to prevent corrosion. Palladium coated copper wire is a common alternative which has shown significant resistance to corrosion, albeit at a higher hardness than pure copper and a greater price, though still less than gold. Special packaging is required in order to protect copper wire and achieve a longer shelf life. The formation of oxides is inherent with this material, so storage and shelf life are issues that must be considered. Annealing and process steps used by manufacturers enhance the ability to use large diameter copper wire to wedge bond to silicon without damage occurring to the die.Ĭopper wire does pose some challenges in that it is harder than both gold and aluminum, so bonding parameters must be kept under tight control. Large diameter copper wire can and does replace aluminum wire where high current carrying capacity is needed or where there are problems with complex geometry. Copper wire has the ability of being used at smaller diameters providing the same performance as gold without the high material cost.Ĭopper wire up to 500 micrometers (0.02 in) can be successfully wedge bonded. Copper is used for fine wire ball bonding in sizes from 10 micrometers (0.00039 in) up to 75 micrometers (0.003 in). Ĭopper wire has become one of the preferred materials for wire bonding interconnects in many semiconductor and microelectronic applications. By 2015, it is expected that more than a third of all wire bonding machines in use will be set up for copper. While possessing higher thermal and electrical conductivity than gold, copper had previously been seen as less reliable due to its hardness and susceptibility to corrosion. This change has been instigated by the rising cost of gold and the comparatively stable, and much lower, cost of copper. The wire bonding industry is transitioning from gold to copper. Wire diameters start from under 10 μm and can be up to several hundred micrometres for high-powered applications. Materials īondwires usually consist of one of the following materials: Wire bonding can be used at frequencies above 100 GHz. Wire bonding is generally considered the most cost-effective and flexible interconnect technology and is used to assemble the vast majority of semiconductor packages. Although less common, wire bonding can be used to connect an IC to other electronics or to connect from one printed circuit board (PCB) to another. Wire bonding is the method of making interconnections between an integrated circuit (IC) or other semiconductor device and its packaging during semiconductor device fabrication. Inside a wire bonded BGA package this package has an Nvidia GeForce 256 GPU
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